Already well known are various types of tripping mechanisms that comprise two hammers hinged on an under guard member and respectively coordinated with the firing pins of the barrels, two tripping rods (hereafter simply referred to as rods) for arresting the hammers in the cocked position, and a trigger that controls separately--through an inertial mass or rocking arm--the movement first of one rod and then of the other for the successive disengagement of the two hammers, the trigger being connected to the rocking arm by means of a pivoting connector mounted on the tail of the trigger and vertically movable therewith.
Similar tripping mechanisms, also known as mono-trigger mechanisms, may further comprise a firing selective device that permits the selective disengagement first of the hammer related to one barrel and then of the hammer related to the other barrel, or vice versa, depending on the requirements of the user.
Among others, there is known for instance from Italian patent application no. 5238-A/87 corresponding to U.S. Pat. No. 4,805,332 of the firm of the present applicant, a selective device consisting of a sliding selector mounted on and movable transversely on an intermediate part of the pivoting connector of the mechanism, and interacting with the rods of the hammers, the sliding selector being arrested in each of the two positions by a spring-loaded piston.
Such an operation, however, calls for a sliding mount of the slide selector on the connector and, even more disadvantageously, a direct access to the mechanism, which involves the disassembly of the mechanism itself from the rocking arm. The operation of the selective device is, therefore, quite troublesome and not so practical.